On the asymptotic behavior of sums ∑n≤xf(n){x/n}k

2020 ◽  
Vol 16 (06) ◽  
pp. 1263-1274
Author(s):  
Liuying Wu ◽  
Sanying Shi

Let [Formula: see text] be an arbitrary real-valued positive nondecreasing function, in this paper we prove that [Formula: see text] [Formula: see text] where [Formula: see text] is the sum given in the title, [Formula: see text] and [Formula: see text] is a positive integer. This improves the result of Mercier and Nowak.

2015 ◽  
Vol 25 (1) ◽  
pp. 79-95
Author(s):  
Ljuben Mutafchiev

Abstract Let λ be a partition of the positive integer n, selected uniformly at random among all such partitions. Corteel et al. (1999) proposed three different procedures of sampling parts of λ at random. They obtained limiting distributions of the multiplicity μn = μn(λ) of the randomly-chosen part as n → ∞. The asymptotic behavior of the part size σn = σn(λ), under these sampling conditions, was found by Fristedt (1993) and Mutafchiev (2014). All these results motivated us to study the relationship between the size and the multiplicity of a randomly-selected part of a random partition. We describe it obtaining the joint limiting distributions of (μn; σn), as n → ∞, for all these three sampling procedures. It turns out that different sampling plans lead to different limiting distributions for (μn; σn). Our results generalize those obtained earlier and confirm the known expressions for the marginal limiting distributions of μn and σn.


2010 ◽  
Vol 42 (03) ◽  
pp. 739-760
Author(s):  
Shoou-Ren Hsiau

Suppose that I 1, I 2,… is a sequence of independent Bernoulli random variables with E(I n ) = λ/(λ + n − 1), n = 1, 2,…. If λ is a positive integer k, {I n } n≥1 can be interpreted as a k-record process of a sequence of independent and identically distributed random variables with a common continuous distribution. When I n−1 I n = 1, we say that a consecutive k-record occurs at time n. It is known that the total number of consecutive k-records is Poisson distributed with mean k. In fact, for general is Poisson distributed with mean λ. In this paper, we want to find an optimal stopping time τλ which maximizes the probability of stopping at the last n such that I n−1 I n = 1. We prove that τλ is of threshold type, i.e. there exists a t λ ∈ ℕ such that τλ = min{n | n ≥ t λ, I n−1 I n = 1}. We show that t λ is increasing in λ and derive an explicit expression for t λ. We also compute the maximum probability Q λ of stopping at the last consecutive record and study the asymptotic behavior of Q λ as λ → ∞.


2011 ◽  
Vol 54 (4) ◽  
pp. 645-653
Author(s):  
André Luiz Flores ◽  
J. Carmelo Interlando ◽  
Trajano Pires da Nóbrega Neto

AbstractLet p be a prime, and let ζp be a primitive p-th root of unity. The lattices in Craig's family are (p –1)-dimensional and are geometrical representations of the integral ℤ[ζp]-ideals 〈1–ζp〉i , where i is a positive integer. This lattice construction technique is a powerful one. Indeed, in dimensions p – 1 where 149 ≤ p ≤ 3001, Craig's lattices are the densest packings known. Motivated by this, we construct (p – 1)(q – 1)-dimensional lattices from the integral ℤ[ζpq]-ideals 〈1 – ζp〉i〈1 – ζq〉j, where p and q are distinct primes and i and j are positive integers. In terms of sphere-packing density, the new lattices and those in Craig's family have the same asymptotic behavior. In conclusion, Craig's family is greatly extended while preserving its sphere-packing properties.


2010 ◽  
Vol 42 (3) ◽  
pp. 739-760 ◽  
Author(s):  
Shoou-Ren Hsiau

Suppose that I1, I2,… is a sequence of independent Bernoulli random variables with E(In) = λ/(λ + n − 1), n = 1, 2,…. If λ is a positive integer k, {In}n≥1 can be interpreted as a k-record process of a sequence of independent and identically distributed random variables with a common continuous distribution. When In−1In = 1, we say that a consecutive k-record occurs at time n. It is known that the total number of consecutive k-records is Poisson distributed with mean k. In fact, for general is Poisson distributed with mean λ. In this paper, we want to find an optimal stopping time τλ which maximizes the probability of stopping at the last n such that In−1In = 1. We prove that τλ is of threshold type, i.e. there exists a tλ ∈ ℕ such that τλ = min{n | n ≥ tλ, In−1In = 1}. We show that tλ is increasing in λ and derive an explicit expression for tλ. We also compute the maximum probability Qλ of stopping at the last consecutive record and study the asymptotic behavior of Qλ as λ → ∞.


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